Long COVID Prevalence Among Workers: Impacts on Workers’ Compensation

By Hon. Susan V. Hamilton, Former Assistant Secretary and Deputy Commissioner, California Workers’ Compensation Appeals Board

Three years ago we were just becoming acquainted with SARS-CoV-2, the virus that causes COVID-19. We hadn’t yet heard the terms, “long COVID,” “long-haulers syndrome,” or “post-acute COVID.” Today, we know that some patients infected with COVID-19 develop recurring or new symptoms weeks or months after becoming infected with the virus. These symptoms may include a chronic cough, shortness of breath on exertion, chest tightness and/or pain, extreme fatigue, muscle pain, headache, brain fog, tachycardia, heart palpitations, abdominal pain, fever, diarrhea, insomnia, problems with memory and/or concentration, and anxiety. While scientific consensus on the definition of this condition is still developing, the Centers for Disease Control has defined “long COVID” as new, returning or ongoing symptoms that a patient experiences four or more weeks after being infected with SARS-CoV-2.

A recent study conducted by the Workers’ Compensation Research Institute, “Long COVID in the Workers’ Compensation System Early in the Pandemic” (Bogdan Savych, WC-23-16, January 2023, WCRI) (https://www.wcrinet.org/reports/long-covid-in-the-workers-compensation-system-early-in-the-pandemic) examined the prevalence of long COVID among workers infected by COVID-19 who received medical treatment and/or income replacement benefits from the workers’ compensation system in the early months of the pandemic. The study findings are significant in informing our understandings of long-COVID and its potential for impact upon the workers’ compensation system.

The Study Design and Dataset

The study used workers’ compensation claims data reported in WCRI’s Data Benchmark Evaluation database. The dataset included all claims where the injury was reported as a COVID-19 infection and the date of infection was between March 1, 2020 and September 30, 2020. For each claim reported as a COVID-19 infection during the study period, the dataset also included information on payments for medical care and indemnity benefit payments through March 31, 2021. Claims that did not have any indemnity payments or medical care payments during the study period were excluded from the dataset. Overall, the study sample included approximately 39,000 claims from 31 states, including California. Using this dataset, the study posed the following five questions:

1. How often do workers with COVID-19 receive medical care beyond a short quarantine and/or recovery period?
2. What is the prevalence of long COVID symptoms among workers with a COVID-19 infection?
3. What body systems are commonly affected by long COVID and what types of medical services are provided to these workers?
4. What are the industry and worker characteristics associated with long COVID?
5. How do rates of long COVID vary across states?

The Study Findings

Question One: How often do workers with COVID-19 receive medical care beyond a short quarantine and/or recovery period?

Question One examined how often workers with COVID-19 received medical care beyond a short quarantine or recovery period. The study reviewed medical care and indemnity payments made on claims one month or more following the date of COVID-19 infection. The good news is that the overwhelming majority of the workers included in the study (67%) only received indemnity payments and were not reported as receiving any medical payments. Presumably, these workers had very mild symptoms and were able to recuperate at home with no medical intervention. Another possibility, the study admits, is that this number may be inflated because many workers used group healthcare rather than workers’ compensation to receive COVID-related treatment in the early days of the pandemic. One-third of the workers in the study received medical care, but no indemnity payments, and about half of those who received medical care also received indemnity payments. While the intensity of the medical care received by these workers varied, only 9% were hospitalized or received care in the ICU. Further, the majority of workers who received medical care, received it within the first month following infection. Only about 5% of these workers received medical care more than four months after infection. The study’s findings suggest the likelihood of developing long COVID following initial infection is low.

Question Two: What is the prevalence of long COVID symptoms among workers with a COVID-19 infection?

Question Two then examined the prevalence of long COVID symptoms among workers with COVID-19. To do so, the study sample included all patients with a COVID-19 diagnosis, even those with mild symptoms. Overall, the prevalence of long COVID among workers included in the study was 7%. However, the prevalence rate of long COVID was higher for workers who received medical treatment and/or indemnity patients following infection. For example, the prevalence of long COVID for workers who received medical care within the first month following infection was 14%. For those workers who received both medical care and indemnity payments within the same timeframe, the prevalence rate for long COVID was 33%. Interestingly, when the type of medical care provided following infection is considered, the prevalence rate for long COVID increased. The prevalence rates for patients who were hospitalized or treated in the ICU was 44% and 74%, respectively. The study does acknowledge that post-acute medical treatment is typically expected in patients who have been treated in the ICU. Thus, the study also examined data indicating medical treatment provided three months or more following infection and the prevalence rates for long COVID were less. It found 28% of patients who had been hospitalized following infection received medical treatment three months or more after infection, and 57% of patients who received treatment in the ICU following infection received medical treatment three or more months after infection. Nonetheless, these percentages do suggest a significant correlation between hospitalization and/or treatment in the ICU following infection with the development of long COVID.

Using the payment information from the dataset, the study was able to identify the costs associated with long COVID. The average medical payment for claims without long COVID was $3,000. However, the average medical costs for workers who had been hospitalized was $50,000 and, for those who had been treated in the ICU, the average cost of medical treatment was more than $150,000. Additionally, indemnity payment data examined in the study suggests that long COVID may have had a significant impact on a worker’s ability to work after infection.

Question Three: What body systems are commonly affected by long COVID and what types of medical services are provided to these workers?

Question Three analyzed the body systems most commonly affected by long COVID and the types of medical services provided to workers with long COVID. This analysis relied on the coding information reported on medical bills for the services provided to workers with COVID-19 in the post-acute period (i.e., one month or more following infection). It found 63% of workers with long COVID had conditions related to their lungs, 29% of workers with long COVID received treatment for conditions related to the heart, and 10% of workers with long COVID reported mental health conditions. The remaining percentage involved a host of other body systems. Approximately half of the workers with long COVID reported conditions involving multiple body systems in the post-acute period. This finding is significant because the study revealed that workers who experienced post-acute symptoms across multiple body systems had higher payments for medical care, higher indemnity benefits, and longer durations of temporary disability indemnity.

The most common medical services provided to workers who received care in the post-acute period were office visits for the evaluation and management of long COVID. The study found that 80% of long COVID patients received these services, and yet they were responsible for less than 10% of all payments made for medical care. Approximately 33% of the workers had laboratory and testing services, and X-rays, and they received prescriptions for medications. Altogether, these services reflected less than 20% of the total payments made during the study period. Even though only about 4% of workers required hospitalization in the post-acute period, the costs for hospitalizations represented 27% of all payments made for medical care during the timeframe analyzed.

Question Four: What are the industry and worker characteristics associated with long COVID?

Question Four examined how the prevalence of long COVID varied by both worker and industry characteristics. The findings are interesting. The data revealed that the likelihood of long COVID increased with the age of workers. Among workers less than 35, 2% to 4% developed long COVID. However, among workers over 55, 10% to 12% developed long COVID. According to the study, this finding is consistent with estimates from other studies that examined the relationship between age and the prevalence of long COVID. This finding seems intuitive, but the same cannot be said for other findings. For example, when the researchers considered all claims, the prevalence of long COVID between women and men was essentially identical (i.e., 6% versus 7%), but when only those claims with medical care were considered, more women (22%) than men (16%) received care for long COVID. The author cautions that sample selection may affect findings.

How geographic factors might impact the development of long COVID was also analyzed. The author reports that conclusions about any such impact differed based on the sample of workers examined. For example, when the sample was all workers, only small differences in the likelihood of developing long COVID were observed in workers who lived in metropolitan areas versus those who did not. However, the conclusions changed when a narrower sample of workers was considered. Those workers who received medical care in the post-acute period and lived outside of metropolitan areas were more likely to develop long COVID than their metropolitan counterparts.

The study also considered the prevalence of long COVID among nine industries: facility living establishments (i.e., assisted living facilities), hospitals, physician and dental offices, clerical and professional, food service, trade, manufacturing and construction, and other. Not surprisingly, the likelihood of developing long COVID for hospital workers was 10% and 11% for workers employed in trade. Workers in six of the other industries had long-COVID prevalence rates between 4% to 9%. The most remarkable finding was that only 3% of workers in the food service industry had medical care for long-COVID. The author attributes this finding to the average age of food service workers, which was the lowest among the nine industries examined.

Question Five: How do rates of long COVID vary across states?

Question Five considered variation in the prevalence of long-COVID among the 31 states included in the study. None of the 31 states had long COVID prevalence rates in excess of 10%, and, among the majority of states, the prevalence rate was between 3% and 8%. The author offers several different possibilities to explain the findings. For example, states had different rules and policies regarding the compensability of a COVID-19 infection. Some states, like California, enacted presumptions that made the claims of certain employees compensable. Other states encouraged workers to use sick leave or salary continuation rather than workers’ compensation indemnity benefits during their recovery from a COVID-19 infection. Also, the intensity of exposure to SARS CoV-2 was different among the 31 states during the study period. Northeast states were affected early on in the pandemic while other states did not experience a surge in infections until later.

Takeaways

We can draw several important conclusions from the study’s findings. Foremost is the positive news that the majority of workers who were infected with COVID-19 had very mild symptoms and only required minimal treatment. Only a small percentage required hospitalization. Next, when considering the population of all workers with a COVID-19 infection, only 7% required treatment in the post-acute period for long COVID. The study also revealed significant differences in costs between COVID-19 infections that did not develop into long COVID and those that did. For COVID-19 infections without long COVID, the average per claim expenditures were less than $3,000. In contrast, claims with long COVID had higher medical payments ($25,000 on average), higher disability indemnity payments, and longer durations of temporary disability than claims without long COVID. And the most significant cost drivers appear to be those claims that required hospitalization or treatment in the ICU.

While the study’s findings give us reason for optimism that the likelihood of developing long COVID is low for the majority of workers who become infected with COVID-19, the author cautions that we have much more to learn and recommends additional research to understand how the pattern of recovery may have changed in subsequent waves of the pandemic, the implications of vaccines and boosters, and the longer-term disability impacts of long-COVID.

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